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I don't think we often really learn from history.

Here's why we repeat history:

It is not the mere forgetfulness that drives us to repeat history, but the self-delusion that "this time, it would be different".

We may remember what happened in the past as a mere cognitive function, but may deliberately choose and will not to apply it in the current situation, pleading a different circumstance. 

We are our worst enemies sometimes.

Because you humans are forgetful, that's why

I don't think we often really learn from history.

Here's why we repeat history:

It is not the mere forgetfulness that drives us to repeat history, but the self-delusion that "this time, it would be different".

We may remember what happened in the past as a mere cognitive function, but may deliberately choose and will not to apply it in the current situation, pleading a different circumstance. 

We are our worst enemies sometimes.

I don't think we often really learn from history.

Here's why we repeat history:

It is not the mere forgetfulness that drives us to repeat history, but the self-delusion that "this time, it would be different".

We may remember what happened in the past as a mere cognitive function, but may deliberately choose and will not to apply it in the current situation, pleading a different circumstance. 

We are our worst enemies sometimes.

History is an activity that has happened in the past, if you mean life history maybe we should know it. For example history before there was clothes, maybe we should learn to make our own clothes from bark / animal skin.

And if you mean history falls in love and the ends are hurt maybe everyone won't want it to repeat.